Creating a custom Week Number variable in a date table

Hi all. I need to create a Week Number column in a date table, but the WEEKNUM function doesn't produce quite the right results.

For the purposes of this variable, weeks start on Sunday. The part where it gets tricky is around the end/beginning of a year.

If the last Sunday of the year falls on December 29, 30, or 31, then I need the following set of 7 days (including the last Sunday in December) to be assigned a week number of 1. If the last Sunday of December falls on December 25, 26, 27, or 28 I need the following set of 7 days (including the last Sunday of December) to be assigned to week 52 or 53 or 54 or whatever is appropiate that year. The end result is that fo some years, there will be some dates in December assigned to week 1, and in other years there will be some days in January that are assigned to week 52 or 53 or 54.

Here are a couple examples of what the output should be:

I appreciate any help!